GOODMAN//Multi-zone//4 zones
Goodman 4-zone heat pump: four rooms on a single 36,000
Only one Series 21 outdoor unit takes four heads: the MST363E21. GOODMAN publishes seven four-head sets for it, all sold as variants. Pick the head for each room: the tool tells you whether the set exists and, if not, which one comes closest.
The question this page answersFour rooms on a single Goodman 36,000: which heads are allowed?
The Goodman 4-zone system in our store
One product page, seven variants: one per published set of heads. The page leads to a price request.
Tool//The four heads
Four heads: is the set published?
Pick the size of the head in each room. The tool looks the set up in GOODMAN's 4-zone table, adds up the heads and, if the set is not there, names the ones that are one head away.
Set 9 + 9 + 9 + 9: heads totalling 36,000 BTU/h
Head total equal to the outdoor unit's rated cooling, 36,000 BTU/h (AirGreen calculation)
The seven published sets
Set published by GOODMAN. It is sold as a variant.
See the 9 + 9 + 9 + 9 variantRoom order does not matter: 12 + 9 + 9 + 9 is the 9 + 9 + 9 + 12 set. GOODMAN's table covers wall and ducted heads; the variants we sell are wall heads. The GOODMAN brochures we read give no maximum ratio between the head total and the rated cooling.
GOODMAN//Four rooms
One outdoor unit for four rooms: what GOODMAN publishes
Three things to know about the 36,000 before connecting four heads to it.
One heating value for four rooms
GOODMAN gives 25,400 BTU/h at -8.3 °C for the whole outdoor unit: with four rooms, that total is what gets shared (source 2, p. 7).
No cassette on the 36,000
The 2018 French-language document marks the cassette "Non offerte" (not offered) on the MST363E21, and the 2021 combination table, headed "Wall mount and ducted", names only wall and ducted heads (source 3, p. 11; source 1, p. 7). The four heads are therefore wall or ducted heads.
Four lines over 24.6 ft: the precharge reads the same either way
GOODMAN precharges the 36,000 for 98.4 ft, which is 4 × 24.6 ft (AirGreen calculation). With four lines each longer than 24.6 ft, the refrigerant to add is the same whether the precharge covers the total or each line: 0.161 oz per foot beyond 98.4 ft (source 1, p. 7).
GOODMAN//4-zone table
The seven sets, from smallest to largest head total
The sets come from GOODMAN's 4-zone table. The totals, the differences from the 36,000 BTU/h rated cooling and the variant numbers are AirGreen's.
| Set (thousands of BTU/h) | Head total | Difference from rated cooling | Variant sold |
|---|---|---|---|
| 9 + 9 + 9 + 9 | 36,000 BTU/h | 0 | MST363E21MCAA-9999 |
| 9 + 9 + 9 + 12 | 39,000 BTU/h | +3,000 BTU/h | MST363E21MCAA-99912 |
| 9 + 9 + 12 + 12 | 42,000 BTU/h | +6,000 BTU/h | MST363E21MCAA-991212 |
| 9 + 9 + 9 + 18 | 45,000 BTU/h | +9,000 BTU/h | MST363E21MCAA-99918 |
| 9 + 12 + 12 + 12 | 45,000 BTU/h | +9,000 BTU/h | MST363E21MCAA-9121212 |
| 9 + 9 + 12 + 18 | 48,000 BTU/h | +12,000 BTU/h | MST363E21MCAA-991218 |
| 12 + 12 + 12 + 12 | 48,000 BTU/h | +12,000 BTU/h | MST363E21MCAA-12121212 |
The 36,000's "standard" combination differs from one document to the next: 9 + 9 + 9 in the 03-21 and 06-21 brochures, 9 + 9 + 9 + 9 in the 2018 French-language document. With no agreement, we use neither.
Compare//Same 36,000
The 36,000 with 4 or 3 zones: the heads
Same outdoor unit, sold as a tri-zone and a 4-zone system. One more room narrows the choice of heads. GOODMAN values from sources 1 and 2, p. 7; the totals are sums.
| On the MST363E21MCAA | 4 zones | 3 zones |
|---|---|---|
| Published sets | 7 | 10 |
| Smallest set | 9 + 9 + 9 + 9, 36,000 BTU/h | 9 + 9 + 9, 27,000 BTU/h |
| Largest head total | 48,000 BTU/h | 48,000 BTU/h |
| 24,000 heads | none | one at most, in a single trio |
| 18,000 heads | one at most | two at most |
| Ports in use | 4 of 4 | 3 of 4 |
See the 3-zone page.
Did you know//GOODMAN documents, AirGreen sums
Three rules hidden in the 36,000's table
The only 1/2-in port among the Series 21 multi-zone units
On the gas side, GOODMAN lists two 3/8-in ports for the 18,000, three for the 27,000, and for the 36,000 three 3/8-in ports plus one 1/2-in port. With 4 zones, one head always takes that 1/2-in port.
Source 1, p. 7Four trios with no fourth head
On the 36,000, 9 + 18 + 18, 12 + 12 + 18, 12 + 12 + 24 and 12 + 18 + 18 are published for 3 zones, but no fourth head turns them into one of the seven sets (AirGreen calculation on the table).
Source 1, p. 7Seven sets, all at 48,000 BTU/h or less
The table holds every four-head set whose total does not exceed 48,000 BTU/h, and no other. The brochures we read do not write it down: the rule shows in the table, set by set.
Source 1, p. 7AirGreen × GOODMAN//Who brings what
Four rooms: who does what
What GOODMAN brings
- The only Series 21 multi-zone outdoor unit that takes four heads, the MST363E21
- A table of seven allowed head sets
- Four 1/4-in liquid ports, one per head
- A SEER of 22.5 and a region V HSPF of 9.0, published for the unit
What AirGreen brings
- An on-site survey of the four rooms, from the smallest to the largest
- The route of four refrigerant lines to a single outdoor unit
- Installation by our refrigeration technicians, under AirGreen's RBQ licence 5645-9605-01
- The choice among the seven sets, room by room
Questions//4 zones
Questions about the Goodman 4-zone
Which heads can go on a Goodman 4-zone system?
9,000, 12,000 and 18,000 heads, in one of the seven sets of the 4-zone table in GOODMAN's 2021 brochure: 9 + 9 + 9 + 9, 9 + 9 + 9 + 12, 9 + 9 + 12 + 12, 9 + 9 + 9 + 18, 9 + 12 + 12 + 12, 9 + 9 + 12 + 18 and 12 + 12 + 12 + 12. All seven are sold as variants.
Does each room keep its own temperature?
In its 2021 brochure, GOODMAN writes that the Series 21 can heat or cool up to four spaces independently with one outdoor unit. Its 2018 French-language document states that a wireless remote comes with each wall head. The documents we read do not say whether one room can heat while another cools.
Can I start with three heads and add the fourth later?
The GOODMAN documents we read say nothing about adding a head later; their table only says which sets exist. The final set has to be one of the seven, and four of the ten trios on the 36,000 lead to none of them, whatever the fourth head: so the first three heads are chosen with the fourth in mind. A 27,000 tri-zone never takes a fourth head.
Does the Goodman 4-zone qualify for Hydro-Québec's LogisVert financial assistance?
No. Since November 26, 2025, Hydro-Québec only accepts ENERGY STAR certified heat pumps, and the MST363E21 is not in the ENERGY STAR list read on November 5, 2026. As early as 2021, GOODMAN's brochure printed that it was not ENERGY STAR certified.
Can the same 36,000 serve two or three rooms?
Yes. For the MST363E21, GOODMAN also publishes eight head pairs and ten trios, sold as dual-zone and tri-zone systems.
Read next//The GOODMAN space
For fewer than four rooms
Four rooms: we start with the floor plan
The four heads have to form one of the seven sets. When a room calls for a bigger head than the table allows, we tell you before the quote, along with the options left.
Sold and installed by AirGreen.Montreal, Laval, Longueuil, the South Shore and the North Shore.
An AirGreen technician assesses the heating and cooling needs, where the units will go and the refrigerant line route on site before proposing a model.
Subclasses 15.8, 15.10 and 16. Gas and oil work is done by a partner holding the required licence.
The equipment is GOODMAN-branded. AirGreen sells it, installs it and services it across Greater Montreal.
Sources
- GOODMAN, "Heat Pump and Air Conditioner Ductless Units", 19 Series and 21 Series, code CB-DL-1921S-HP 03-21, p. 2 and 7. GOODMAN document kept in AirGreen's files.
- GOODMAN, same brochure, revision CB-DL-1921S-HP 06-21, p. 7.
- GOODMAN, "Thermopompe et climatiseur simple et multizones" (French-language document), code CB-GDuctless2018-FR 10.18, p. 9 and 11.
- ENERGY STAR, certified heat pumps (dataset w7cv-9xjt), Canadian market, read November 5, 2026. energystar.gov
- Hydro-Québec, "LogisVert Efficient Homes Program – ENERGY STAR® Heat Pump", partner notice of September 25, 2025 (required from November 26, 2025). hydroquebec.com
Read and dated by AirGreen. Capacities and limits are the ones GOODMAN publishes; a real installation can give other values.